Grinding wheel with provision for coolant application



Nov. 19, 1963 c. R. GRAGE 3,110,993

GRINDING WHEEL WITH PROVISION FOR COOLANT APPLICATION Filed July 18, 1962 JMJAHhZrU as wez R. Erage 33 www United States Patent 3,116,993 GRHNDENG WHEEL WETH PRGVlSlUN F62 COGLANT APPLECATHON Casper R. Grage, Escondido, @alih, assignor to Continental Granite Corp, Escondido, Calif., a corporation of California Filed July 18, 1962, Ser. No. 210,795 2 Claims. (Cl. 51267) This invention relates to grinding wheels and has as its purpose to provide an improved grinding wheel for use on portable grinders and especially those employed in the finishing of granite and other stone surfaces.

In the finishing of granite and other stone surfaces, much of the work is done by craftsmen using portable hand-held motor driven grinders; and heretofore these grinders always operated dry, i.e. no attempt was made to wet the surface being ground. As a result, a tremendous amount of dust was formed which, of course, was anything but conducive to healthy Working conditions.

With a view toward overcoming this obvious objection, this invention has as its purpose and object to pro vide a grinding wheel so designed and constructed that a liquid coolant, such as water, fed to the wheel will flow through the interstices of its porous body to issue therefrom only at its working surface.

More specifically, it is an object of this invention to provide a grinding wvheel of the character described, which has a porous body having opposed work performing and liquid coolant receiving surfaces, and means on its intervening surface which connects or joins the liquid-receiving and work performing surfaces, impervious to the passage of water or other liquid so that liquid which enters the interstices of the porous body can only leave the same at its work performing surface.

Still another object of this invention is to provide an inexpensive, simple grinding wheel, having a flat circular work performing surface normal to the axis of the wheel and an opposite smaller diameter coolant receiving surface surmounted by a shallow, cup-like disc, to which liquid coolant may be fed, and from which such coolant reaches the porous body through holes in the bottom of said cup-like disc.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a perspective view of a portable hand held grinder of the type used in finishing granite and other stone surfaces, equipped with a grinding wheel embodying this invention;

FIGURE 2 is a view partially in side elevation and partially broken away and in section, illustrating the construction of the grinding wheel of this invention; and

FIGURE 3 is a fragmentary cross-sectional view taken through FIGURE 2 on the plane of the line 3-3.

Referring now more particularly to the accompanying drawing, the numeral 5 designates an electric motor driven grinder of the type commonly used for manually finishing the surfaces of granite and other similar material. As is customary, the grinder 5 has a pair of handles 6 and 7, by which the operator holds the grinder, and an electric motor, not shown, Within the housing of "ice 2 the grinder, to drive a vertical, downwardly directed spindle 8, to which a grinding wheel 9 is detachably secured.

The grinding wheel 9 comprises a frusto-conical body of abrasive material having an inverted cup-shaped formation with a top wall lit, the upper surface 11 of which is substantially fiat, and a conical side wall 12. Because of the conical shape of its side wall, the body is, of course, larger in diameter at its bottom than at its top, a fact which is of advantage to this invention, as will appear hereinafter. The downwardly facing edge of the side wall 12 is quite broad and flat and provides the work performing surface 13 of the grinding wheel.

To mount the grinding wheel on the spindle 3, the latter is threaded and the top wall it? of the wheel has an internally threaded bushing 14 fixed therein at its center and threaded onto the spindle.

The body 9 is formed of porous abrasive material and thus has a myriad of interconnected interstices through which liquid may seep. This attribute of the abrasive material is utilized to keep the work performing surface 13 of the wheel wet. To this end, the top wall iii of the wheel has a shallow cup-shaped member -15 mounted thereon to provide a reservoir for Water or other liquid coolant which reaches the top surface 11 of the porous body through holes 16 in the flat bottom of the cupshaped member. These holes are arranged in a circular row directly adjacent to the junction between the bottom wall 17 and the side wall 18 of the shallow cup-shaped member. Centrifugal force thus throws the liquid fed to the reservoir into these holes, and to further assure passage of the liquid through the holes, and prevent loss thereof over the rim of the reservoir, its side wall 18 is inwardly inclined or undercut so that the cup-shaped member has a reentrant formation.

A hole r19 through the center of the bottom wall 17 accommodates the spindle 8. Thus, when the parts are assembled, as shown in FIGURE 2, the shallow cup-shaped member is clamped between the body of the grinding wheel and the underside of a flange 20 on the spindle.

Water or other liquid coolant is delivered to the cupshaped member 15 through a supply line 21, having a nozzle 22 positioned to discharge into the mouth of the cup-shaped member at a rate determined by the setting of a valve 23. As the coolant passes through the holes 16 it flows over the top surface 11 of the porous body which is preferably slightly spaced from the underside of the cup-shaped member 15 for most of its area. To provide this space, the bottom wall 17 of the cupshaped member has a downwardly projecting rim 24 which seats against the marginal edge portion of the top of the porous body.

Because of the porous nature of the body of the grinding wheel, the liquid delivered to its top surface 11 enters the pores or interstices of the body, and unless restrained would be discharged by centrifugal force at the outer surface of its sloping side wall 12. 'To prevent this, the exterior surface 25 of the side wall is coated with a liquidirnpervious substance, such as epoxy resin, varnish, or the like, as indicated at 26.

The coating 26 effectively prevents the discharge of liquid coolant through the side of the grinding wheel and in cooperation with the centrifugal force acting upon this coolant because of the downwardly increasing diameter of the body, directs all of it down to the work performing surface 13.

Although the shallow cup-shaped member 15 has been shown as separate from the body of the grinding wheel, and as simply clamped in place, it could be secured to the top face of the grinding wheel, if desired. In any event, it is preferable to have the exterior of its side wall 18 flush with the side of the body.

From the foregoing description taken with the accom- 3 panying drawing, it will be apparent that this invention greatly reduces the likelihood of stone finishers contracting pneumonocaniofis, since it effectively eliminates the dust which heretofore attended the use of grinders used by these craftsmen.

What is claimed as my invention is:

1. In an abrading tool having a power driven rotatable spindle:

A. a cup-shaped grinding wheel of poorus abrasive material having 1) a top wall with a fiat upper surface and with a coaxial hole in which said spindle is engaged, and

(2) a circumferential side wall extending down- Wardly from the top wall, said side wall (a) having its inner and outer surfaces coaxial with said hole in the top wall,

(b) having substantial thickness in the radial direction, and

() having a substantially flat bottom face which provides the work performing surface of the wheel;

B. a substantially cup-shaped having (1) a substantially fiat bottom wall with a spindle receiving hole at its center and with a plurality of oircumferentially spaced coolant outlet holes near its outer edge,

(2) a circumferential side wall extending upwardly and radially inwardly from the bottom wall, and

(3) a downwardly proiecting rim around the marginal edge of the bottom wall;

C. securement means on the spindle holding the grinding Wheel and the reservoir member thereon in coaxial relationship, with the rim on the reservoir member engaging the flat upper surface of the wheel around the marginal edge portion thereof to hold the bottom wall of the reservoir member spaced above said upper surface of the wheel;

D. coolant supply means on the tool comprising a duct having an outlet alongside the spindle and spaced above the bottom wall of the reservoir member, for introducing liquid coolant into the reservoir member; and

E. means on the outer circumferential surface of the grinding Wheel providing a coating thereon which is impervious to liquid coolant so that coolant introduced into the reservoir member when the grinding wheel is rotating, and which flows down into the pores of the grinding wheel through the coolant outlet holes in the reservoir member, can pass out of reservoir member the grinding wheel only through the work performing surface thereof.

2. In combination with a grinding tool having a power driven downwardly projecting rotatable spindle on which is removably mounted a cupshaped porous grinding Wheel of the type having an end Wall with a substantially flat upper surface and a circumferential side wall with substantial thickness radially and with a flat bottom that provides the work performing surface of the wheel, means for conducting liquid coolant to the work performing surface of the wheel comprising:

A. a bowl-shaped reservoir member coaxi ailly secured to the spindle above the grinding wheel and having (1) a bottom wall with (a) a coaxial hole therein through which the spindle extends and (b) a plurality of circumferentially spaced coolant outlet holes, (2) a circumferential side wall which extends upwardly from the bottom Wall, and (3) a downwardly projecting circumferential rim which engages the upper surface of the grinding wheel around the marginal edge thereof to prevent escape of liquid from between the reservoir member and the wheel;

B. means on the tool for introducing liquid coolant into the reservoir member, said means having an outlet alongside the spindle; and

C. means providing a coating on the outer circumferential surface of the side wall of the Wheel which is impervious to liquid coolant, so that liquid coolant introduced into the reservoir member and passing downwardly into the pores of the wheel through the coolant holes in the reservoir member is constrained to flow downwardly through the pores of the wheel and to leave the wheel through its Work performing surface.

References Cited in the file of this patent UNITED STATES PATENTS 436,892 Harrington Sept. 23, 1890 716,171 Bassstt Dec. 16, 1902 2,178,835 Hudson Nov. 7, 1939 2,380,332 Scheer July 10, 1945 2,697,878 Oberley Dec. 28, 1954 2,735,249 Mart-in et a1. Feb. 21, 1956 2,800,754 Robertson July 30, 1957 2,840,960 Booth July 1, 1958 FOREIGN PATENTS 628,456 Canada Oct. 3, 1961 

2. IN COMBINATION WITH A GRINDING TOOL HAVING A POWER DRIVEN DOWNWARDLY PROJECTING ROTATABLE SPINDLE ON WHICH IS REMOVABLY MOUNTED A CUP-SHAPED POROUS GRINDING WHEEL OF THE TYPE HAVING AN END WALL WITH A SUBSTANTIALLY FLAT UPPER SURFACE AND A CIRCUMFERENTIAL SIDE WALL WITH SUBSTANTIAL THICKNESS RADIALLY AND WITH A FLAT BOTTOM THAT PROVIDES THE WORK PERFORMING SURFACE OF THE WHEEL, MEANS FOR CONDUCTING LIQUID COOLANT TO THE WORK PERFORMING SURFACE OF THE WHEEL COMPRISING: A. A BOWL-SHAPED RESERVOIR MEMBER COAXIALLY SECURED TO THE SPINDLE ABOVE THE GRINDING WHEEL AND HAVING (1) A BOTTOM WALL WITH (A) A COAXIAL HOLE THEREIN THROUGH WHICH THE SPINDLE EXTENDS AND (B) A PLURALITY OF CIRCUMFERENTIALLY SPACED COOLANT OUTLET HOLES, (2) A CIRCUMFERENTIAL SIDE WALL WHICH EXTENDS UPWARDLY FROM THE BOTTOM WALL, AND (3) A DOWNWARDLY PROJECTING CIRCUMFERENTIAL RIM WHICH ENGAGES THE UPPER SURFACE OF THE GRINDING WHEEL AROUND THE MARGINAL EDGE THEREOF TO PREVENT ESCAPE OF LIQUID FROM BETWEEN THE RESERVOIR MEMBER AND THE WHEEL; B. MEANS ON THE TOOL FOR INTRODUCING LIQUID COOLANT INTO THE RESERVOIR MEMBER, SAID MEANS HAVING AN OUTLET ALONGSIDE THE SPINDLE; AND C. MEANS PROVIDING A COATING ON THE OUTER CIRCUMFERENTIAL SURFACE OF THE SIDE WALL OF THE WHEEL WHICH IS IMPERVIOUS TO LIQUID COOLANT, SO THAT LIQUID COOLANT INTRODUCED INTO THE RESERVOIR MEMBER AND PASSING DOWNWARDLY INTO THE PORES OF THE WHEEL THROUGH THE COOLANT HOLES IN THE RESERVOIR MEMBER IS CONSTRAINED TO FLOW DOWNWARDLY THROUGH THE PORES OF THE WHEEL AND TO LEAVE THE WHEEL THROUGH ITS WORK PERFORMING SURFACE. 